The present invention relates to a camera on which a film pack adapted for accommodating layered instant photographic films is mounted.
Hitherto, there is known a camera on which a film pack adapted for accommodating layered instant photographic films is mounted inside a frame member having an aperture, the film pack having such a structure that the aperture of the frame member being closed by a shielding plate. In such a type of camera, there is one having a display unit for displaying the number of residual films within the mounted film pack wherein when a new film pack is mounted, there is performed an initialization processing such that the displayed content is altered into the number of films accommodated in the new film pack. The shielding plate consists of a plastic member or the like having a sufficient thickness since there is a need to provide a sufficient shielding property so as to protect the layered films from the external light. After an exchange of film packs is performed, for example, at the time when the rear cover is closed, the display unit displays a predetermined number (for example 10) corresponding to the number of films layered within the new film pack, and upon receipt of an electric power from a built-in battery, first the shielding plate is discharged. Thereafter, in accordance with a photographic operation, a top layer of film of the layered films is exposed, so that a developer, which is stored in a part of the exposed film beforehand, is equally diffused in the film to develop and discharged. As a result, the number of residual films is decreased by 1 and then displayed on the display unit.
According to the above-mentioned camera, when the rear cover is closed after an exchange of the film packs, it is always decided that a new film pack is mounted, and the initialization processing is performed. For example, the display unit displays the number of films accommodated in the new film pack. A photographer confirms the photography-possible number of films through an observation of the number of films displayed on the display unit.
There is a case where a photographer performs such an operation that he erroneously opens the rear cover at the time when the layered films still remain in the film pack, and he becomes aware of his error and then immediately closes the rear cover. For example, the above-mentioned operation is performed at the time when five sheets of layered films remain in the film pack, the camera decides, in view of the fact that the film pack is mounted and then rear cover is closed, that a new film pack is mounted. According to such a type of camera, when a sheet of film is discharged from the film pack, the camera decides that the shielding plate is discharged, and although the number of residual films is actually four sheet, the display unit displays the number of residual films xe2x80x9810xe2x80x99. For this reason, the conventional camera is associated with a problem that the number of residual films, which is actually possible to be used for photography, is different from the number of residual films, which is displayed on the display unit.
In view of the foregoing, it is an object of the present invention to provide a camera capable of performing a proper control according to a situation, for example, in such a manner that in the event that at the time when layered films remain in a film pack, the film pack is re-mounted, the number of the residual films is accurately displayed.
To achieve the above-mentioned object, the present invention provides a camera wherein a plurality of instant photographic films are layered, a film pack having a shielding plate for shielding the layered films is loaded, the shielding plate is first discharged by a power of a built-in battery and thereafter a top layer of film of the layered films is exposed in accordance with a photographic operation, and an exposed film is discharged while developed, said camera comprising:
a shielding plate detection section for detecting a presence of the shielding plate of the loaded film pack; and
a control section for performing a control in accordance with a detection result by said shielding plate detection section.
According to the camera of the present invention, the presence of the shielding plate of the loaded film pack is detected. This feature makes it possible to distinguish the state in which a new film pack is loaded and the state that a film pack exchange operation is erroneously performed on the film pack involved in photograph on halfway, and then perform a proper control.
In the camera according to the present invention as mentioned above, it is preferable that said shielding plate detection section detects whether one discharged by a present discharge operation is the shielding plate, in accordance with the shielding plate of the loaded film pack or a load at the time of a discharge operation for the film.
The shielding plate is formed by a plastic member or the like having a sufficient thickness, and the material of the shielding plate is larger in hardness and rigidity than the material of the film. For this reason, the load current of the feeding motor at the time of discharge of the shielding plate and the voltage drop due to the internal impedance of the built-in battery are larger than the load current at the time of discharge of the film and the voltage drop. Utilization of this feature makes it possible to detect whether it is concerned with the shielding plate through comparison of magnitude of the load current and the voltage drop. In this case, as shown in the embodiments, which will be described later, it is possible to use a relatively simple circuit structure.
In the camera according to the present invention as mentioned above, it is preferable that the camera further comprises a display unit for displaying a state of the camera, and said control section controls a display content of said display unit in accordance with a detection result by said shielding plate detection section.
As states of the camera, there are raised states of a counter for storing the number of films, a film speed, a lens position, an electronic flash control mode (on/off/auto) as the exposure mode, and an exposure correction (darken/normal/lighten). The control as mentioned above makes it possible to distinguishably display the state of the camera at the time when the new film pack is loaded and the state of the camera in half way of photography.
In the camera according to the present invention as mentioned above, it is preferable that the camera further comprises a display unit for displaying the number of residual films within the loaded film pack,
wherein said control section comprises a storage section for storing the number of residual films within the film pack before a film pack exchange operation, and a display control section for causing said display unit to display a predetermined number corresponding to the number of films layered within the film pack having the shielding plate, or a number in which one is subtracted from the number of residual films stored in said storage section, according as said shielding plate detection section detects that now discharged one is the shielding plate, in a case where the film pack exchange operation is made.
The above-mentioned xe2x80x9cfilm pack exchange operationxe2x80x9d includes not only the operation wherein the loaded film pack is removed and a new film pack is loaded, but also an operation wherein the loaded film pack is removed and the removed film pack is loaded as it is, and an operation wherein an operation (for example, an operation of opening the rear cover) for removing the film pack is performed, and an operation (for example, an operation of closing the rear cover) for completing the loading of the film pack is performed without removing the film pack.
According to this arrangement, in the event that the shielding plate is discharged, the display unit may display a predetermined number corresponding to the number of films layered in a new film pack. And in the event that a film is discharged, the display unit may display the number in which one is subtracted from the number of residual films stored in the storage section. For this reason, even if it is concerned with such situations that at the time when layered films remains in the film pack, an exchange operation is performed on the film pack, it is possible to exactly display the number of residual films on the display unit, without bringing about, as in the former camera, such a situation that the photography-possible number of residual films is different from the number of residual films displayed on the display unit.
In the camera according to the present invention as mentioned above, it is acceptable that said camera adapts for loading thereonto a film pack recording film information related to an incorporated film, and
said camera has a sensor for reading the film information recorded on the film pack, and said control section causes said sensor to read the film information upon receipt of that said shielding plate detection section detects the shielding plate.
Here, the film information related to an incorporated film implies the number of films stored in the film pack, and a film speed.
This arrangement makes it possible to perform a control of a camera in accordance with the film information read by the sensor.
Further, in the camera according to the present invention as mentioned above, it is acceptable that said control section performs an initialization on at least one portion of element of said camera upon receipt of that said shielding plate detection section detects the shielding plate.
Here, it is preferable that xe2x80x9cat least one portion of elementxe2x80x9d referenced above is one or more among a lens position, an electronic flash control mode as the exposure mode, and an exposure correction. Upon receipt of that the shielding plate is detected, the initial setting is performed on xe2x80x9cat least one portion of elementxe2x80x9d. This feature makes it possible to enhance an operational efficiency.
As mentioned above, according to the present invention, it is possible to perform a proper control according to a situation, for example, in such a manner that in the event that at the time when layered films remain in a film pack, the film pack is re-mounted, the number of the residual films is accurately displayed.